rtpdec: Support H263 in RFC 2190 format

This is different from the "modern" RTP payload formats for H263
as defined by RFC 4629, 2429 and 3555. According to the newer RFCs,
this old one is to be considered deprecated and only be used for
interoperating with legacy systems.

Signed-off-by: Martin Storsjö <martin@martin.st>

1 files changed, 184 insertions, 0 deletions

diff --git a/libavformat/rtpdec_h263_rfc2190.c b/libavformat/rtpdec_h263_rfc2190.c
new file mode 100644
index 0000000000..baec6a427c
--- /dev/null
+++ b/libavformat/rtpdec_h263_rfc2190.c
@@ -0,0 +1,184 @@
+/*
+ * RTP H.263 Depacketizer, RFC 2190
+ * Copyright (c) 2012 Martin Storsjo
+ * Based on the GStreamer H.263 Depayloder:
+ * Copyright 2005 Wim Taymans
+ * Copyright 2007 Edward Hervey
+ * Copyright 2007 Nokia Corporation
+ * Copyright 2007 Collabora Ltd, Philippe Kalaf
+ * Copyright 2010 Mark Nauwelaerts
+ *
+ * This file is part of Libav.
+ *
+ * Libav is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * Libav is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "avformat.h"
+#include "rtpdec_formats.h"
+#include "libavutil/intreadwrite.h"
+#include "libavcodec/get_bits.h"
+
+struct PayloadContext {
+    AVIOContext *buf;
+    uint8_t      endbyte;
+    int          endbyte_bits;
+    uint32_t     timestamp;
+};
+
+static PayloadContext *h263_new_context(void)
+{
+    return av_mallocz(sizeof(PayloadContext));
+}
+
+static void h263_free_context(PayloadContext *data)
+{
+    if (!data)
+        return;
+    if (data->buf) {
+        uint8_t *p;
+        avio_close_dyn_buf(data->buf, &p);
+        av_free(p);
+    }
+    av_free(data);
+}
+
+static int h263_handle_packet(AVFormatContext *ctx, PayloadContext *data,
+                              AVStream *st, AVPacket *pkt, uint32_t *timestamp,
+                              const uint8_t *buf, int len, int flags)
+{
+    int f, p, i, sbit, ebit; /* Corresponding to header fields in the RFC */
+    int header_size;
+
+    if (data->buf && data->timestamp != *timestamp) {
+        /* Dropping old buffered, unfinished data */
+        uint8_t *p;
+        avio_close_dyn_buf(data->buf, &p);
+        av_free(p);
+        data->buf = NULL;
+    }
+
+    if (len < 4) {
+        av_log(ctx, AV_LOG_ERROR, "Too short H.263 RTP packet: %d\n", len);
+        return AVERROR_INVALIDDATA;
+    }
+
+    f = buf[0] & 0x80;
+    p = buf[0] & 0x40;
+    if (!f) {
+        /* Mode A */
+        header_size = 4;
+        i = buf[1] & 0x10;
+    } else if (!p) {
+        /* Mode B */
+        header_size = 8;
+        if (len < header_size) {
+            av_log(ctx, AV_LOG_ERROR,
+                   "Too short H.263 RTP packet: %d bytes, %d header bytes\n",
+                   len, header_size);
+            return AVERROR_INVALIDDATA;
+        }
+        i = buf[4] & 0x80;
+    } else {
+        /* Mode C */
+        header_size = 12;
+        if (len < header_size) {
+            av_log(ctx, AV_LOG_ERROR,
+                   "Too short H.263 RTP packet: %d bytes, %d header bytes\n",
+                   len, header_size);
+            return AVERROR_INVALIDDATA;
+        }
+        i = buf[4] & 0x80;
+    }
+    sbit = (buf[0] >> 3) & 0x7;
+    ebit =  buf[0]       & 0x7;
+
+    buf += header_size;
+    len -= header_size;
+
+    if (!data->buf) {
+        /* Check the picture start code, only start buffering a new frame
+         * if this is correct */
+        if (!f && len > 4 && AV_RB32(buf) >> 10 == 0x20) {
+            int ret = avio_open_dyn_buf(&data->buf);
+            if (ret < 0)
+                return ret;
+            data->timestamp = *timestamp;
+        } else {
+            /* Frame not started yet, skipping */
+            return AVERROR(EAGAIN);
+        }
+    }
+
+    if (data->endbyte_bits || sbit) {
+        if (data->endbyte_bits == sbit) {
+            data->endbyte |= buf[0] & (0xff >> sbit);
+            data->endbyte_bits = 0;
+            buf++;
+            len--;
+            avio_w8(data->buf, data->endbyte);
+        } else {
+            /* Start/end skip bits not matching - missed packets? */
+            GetBitContext gb;
+            init_get_bits(&gb, buf, len*8 - ebit);
+            skip_bits(&gb, sbit);
+            if (data->endbyte_bits) {
+                data->endbyte |= get_bits(&gb, 8 - data->endbyte_bits);
+                avio_w8(data->buf, data->endbyte);
+            }
+            while (get_bits_left(&gb) >= 8)
+                avio_w8(data->buf, get_bits(&gb, 8));
+            data->endbyte_bits = get_bits_left(&gb);
+            if (data->endbyte_bits)
+                data->endbyte = get_bits(&gb, data->endbyte_bits) <<
+                                (8 - data->endbyte_bits);
+            ebit = 0;
+            len = 0;
+        }
+    }
+    if (ebit) {
+        if (len > 0)
+            avio_write(data->buf, buf, len - 1);
+        data->endbyte_bits = 8 - ebit;
+        data->endbyte = buf[len - 1] & (0xff << ebit);
+    } else {
+        avio_write(data->buf, buf, len);
+    }
+
+    if (!(flags & RTP_FLAG_MARKER))
+        return AVERROR(EAGAIN);
+
+    if (data->endbyte_bits)
+        avio_w8(data->buf, data->endbyte);
+    data->endbyte_bits = 0;
+
+    av_init_packet(pkt);
+    pkt->size         = avio_close_dyn_buf(data->buf, &pkt->data);
+    pkt->destruct     = av_destruct_packet;
+    pkt->stream_index = st->index;
+    if (!i)
+        pkt->flags   |= AV_PKT_FLAG_KEY;
+    data->buf = NULL;
+
+    return 0;
+}
+
+RTPDynamicProtocolHandler ff_h263_rfc2190_dynamic_handler = {
+    .codec_type        = AVMEDIA_TYPE_VIDEO,
+    .codec_id          = CODEC_ID_H263,
+    .parse_packet      = h263_handle_packet,
+    .alloc             = h263_new_context,
+    .free              = h263_free_context,
+    .static_payload_id = 34,
+};